Ice throw: Sarlak and Sorensen

Sariak & Sorensen. Analysis of Throw distances of detached objects from horizontal-axis wind turbines

Ice throw from an industrial wind turbine is a concern for Iowans. The current Dickinson County Conditional Use Ordinance has setback of 1200 ft from turbine to nearest point of home, and proposed change to 1,600 ft. These are predictions from the Department of Wind Energy in Denmark. With tip speeds of about 70 M/S (normal operating conditions), pieces of blade (with weights in the range of approx. 7-16 ton) would be thrown out 700 meters (2296 ft).  Turbines operating at the extreme tip sped of 150 m/s may be subject to blade thrown up to 6561 feet or 1.243 miles from the turbine. Documented ice throw of 600 meters (1968 ft). Ice throw and component liberation distance 328 feet @ stand still up to 1.24 miles for blade throw during an overspeed event. 

Table 1 with distances of wind turbines from human structures:

            France & Germany 5280 ft

            Rural Manitoba, Canada 6500 ft

            Riverside, CA      10560 ft